A centralized tissue culture facility is more economical than individual investigators perform their own cell culture. The proposed core would be an expansion to accommodate this program project of a tissue culture core that has been in operation since 1980 in the Division of Endocrinology. Reasons for establishing and maintaining a common tissue culture core include the following: 1. Quality control of cell lines, culture techniques, and solutions 2. Bulk preparation of cells and media gives an economical advantage 3. Optimal use of time, equipment and supplies 4. Experienced technicians 5. Consistency between preparations A centralized tissue culture facility is the most efficient means for maintaining cell lines. The cell lines are catalogued and frozen as back-up stocks in liquid nitrogen tanks equipped with alarm systems to prevent loss of important cell lines. All cell lines are screened for mycoplasma detection twice per year. Purchase of fetal calf serum and media in bulk is certainly more cost-effective. Prescreening of 3 to 4 sources of serum for optimal cell growth before purchase is most efficiently accomplished in the core facility. Media and PBS can be prepared at 10, 20, or 30 liters at a time and then tested before use. Bulk ordering of plasticware is also more cost effective. The incubators and hoods are checked and maintained on a periodic basis at specific scheduled times.